The invention relates to a hydraulic vehicle brake system as defined hereinafter.
U.S. Pat. No. 4,936,637 discloses a hydraulic vehicle brake system with a hydraulically controllable throttle valve between the master brake cylinder, and two independently controllable anti-lock valve assemblies of two wheel brakes in one brake circuit. A second brake circuit of the vehicle brake system is embodied in the same way. The throttle valve has a control inlet and is controllable by means of an outlet pressure from a return pump, the inlet to which is connected to the anti-lock valve assembly. The disposition of only a single adjustable throttle valve for both anti-lock valve assemblies and their wheel brakes has the disadvantage that in the anti-lock mode, brake pressure increases in the two wheel brakes can proceed variously fast, depending on whether brake pressure increases are taking place in one or both wheel brakes simultaneously. Moreover, the known adjustable throttle valve is complicated in structure, and because of its construction it hinders a rapid brake pressure decrease in the wheel brakes whenever the brake pedal is rapidly released during an anti-lock mode.
A brake system known from U.S. Pat. No. 4,099,793 for a motorcycle has a hydraulically controllable 2/2-way valve, combined with a throttle, located between the master brake cylinder, which by way of example is manually controllable, and an anti-lock valve assembly; the control inlet of this 2/2-way valve likewise communicates with the outlet of a return pump. The open position of a the valve is effected by an opening spring. This combination of a 2/2-way valve and a separately disposed throttle also hinders rapid brake pressure reductions in the wheel brake.